Downdraft carburetor



Aug. 22, 1933. B. BEARD DOWNDRAFT CARBURETOR Original Filed July 12,1950 INVENTOR. BERT Bram).

BY M W ATTORNEY.

Patented Aug. 22, 19 33 I v A I I UNITED STATES: PATENT orrics QDOWNDRAFT caanu mtroa Bert Beard, Detroit, Mich, assignor to GeorgeMpliollity, Detroit, Mich. 1

,Application July 12, 1930. serial No. 461,494,

Renewed November 9, 1932' 8 Claims. (01. 251-34) This invention relatesto a downdraft carbu- 2, line 28-31. An idling and low speed fuel ar-''retor having a high speed fuel nozzle combined rangement Y-Z is of awell known typ as with an air vented compensating nozzle. shownconnected to the annular chamber W The specific object of this inventionis toapthrough the restricted passage X, but as this is 5 ply anaccelerating pump to-the air vented comnot part of this invention itsspecific details need pensating nozzle, and a constant gravity headnotbe described. 1 p to the high speed fuel nozzle. 8 l v Fig. 2 shows amodificationof the construc- In the figures all-the essential parts oftheintion shown in Fig. 1 with the valve N located vention are arrangedon one plane so as to sim-' outside of the pump cylinder B and in thefloat plify the description. g I chamber-A. An arm vV attached as abracket Fig. 1 shows the preferred construction. p to the arm U isarranged to engage with the up! 2 shows a modification of Fig. 1.- perendof the valveNwhen the throttle is opened In the figures A is thefloat chamber containwide. n ing the usual float mechanism which is nopart Operation.

of this invention, B is the pump cylinder 10- l I cated wholly withinthe float chamber, C is the When the engine is idling on the low speedguiding portion of a piston which consists of passages XY--.Z. the checkvalve F is in the the parts C, D, E and F. B being the piston positionshown, that it is suspended on the step proper which comes in contactwith the fuel. on the extension-C, and fuel thus freely passes Thispiston D is carried on C! which is an exfrom A through G into the pistoncylinder B, tension from C. A spring Eseparates the part as the checkvalve F leaves the perforation in C from D. The piston D is perforated,and the D open- When the throttle is opened the fuel in perforation is.closed by an annular check valve B acting on the check valve F raises itagainst the F. This'check valve F is carried on a step on perforatedpiston D thus closing this perforation 5 the extension C. The fuelentrance to the cyland'trapping the fuel in the cylinder B, which inderB is through the opening G located betherefore is forced through H intothe perforated low the level in the fioat chamber A. The fuel passage J.The fuel discharges from J into the outlet from the cylinder B isthrough the reannular passage K and so into the throat of strictedorifice H, then through the perforated the venturi P. Normally airenters about V and o tube J to the annular nozzle'K. In the center fiowsinto the annular chamber W which surof the annular nozzle K an airpassage M is rounds J, and this air enters through the per provided forstill further a.tomizing the fuel. foration and thus mingles with thefuel therein. In the bottom of the cylinder 13 a valve N is lo-- Whenthe throttle is open beyond half way that cated, which is adapted toengage with the ex-. is to say at speeds corresponding to 55 miles 35tension C. Whenthe piston descends this valve per hour, C the extension"from the piston C N is opened and so admits fuel to a passage 0 engageswith the valve N, then the fuel is forced which discharges into thethroat of a Venturi up 0 as well as through J. This fuel discharges tubeP, into the throat of which the annular at 0 below the level in thefloat chamber A. nozzle K also discharges. It will be noted thatHence-if the throttle is held wide open on a hill 46 the passage 0discharges into P morethan A? for example, and the engine speed drops sothat below the level in the float chamber A. The practically nodepression exists in the venturi P venturi P discharges into the mixtureoutlet Q then fuelfiows from A to B past the valveN in which is locatedthe throttle R. vThis throt-- up the passage 0, into the-venturi P, andcontle R is controlled by a lever S, which is manna 'tinues to flowunder the infiuenceof gravity head 45 ally controlled at one end and isconnected atinthefioat chamber A. This feature is disclosed l00 theother end through the rod T with the rod in the applicant's copendingapplication Serial] U. U engages with the upper side of the pis- No.422,516 filed January 22, 1930. The function ton C so that when thethrottle R. is opened of the spring E is to provide a, followup for thepiston CD--E--F descends. The perfothe pump discharge so that when thethrottle is so rated tube J is vented to the air entrance throughsnapped opened the pump continues to disthe passage V which communicateswith an ancharge. This well known feature is taken from nular chamber W,which surrounds the perthe Munson Patent 1,228,692. As theoutlet offorat'ed tube J. This being the well known 0 into P is below the fuellevel in the float chard- Daimler construction as shown in the Britishher there isno necessity to connect. the assageO v: 5t Daimler PatentNo. 10,786 of the year 1885 page with the pump cylinder B, and if t evalve N is removed from the bottom of the cylinder 13, as shown in Fig.2, substantially equivalent results will be obtained. The valve N isthen operated by an arm V' attached to V so that the valve N opens atthe same angular position of the throttle R as the valve N in Fig. 1opens.

-What I claim is:

1. In a carburetor having an air entrance, a mixture outlet, a throttlevalve therein, a mixture chamber intermediate the throttle and the airentrance, a constant level fuel supply chamber, an accelerating pump fedtherefrom, a piston in said pump, means interconnecting said piston withsaid throttle, an outlet from said pump discharging into said mixingchamber said outlet being vented to the: atmosphere at a point above thelevel in said supply chamber, a second outlet from said pump discharginginto said mixture chamber at a point below the level of said fuelsupply, valve means engaging with said pump controlling said second fueloutlet whereby said second fuel outlet is only in operation when thethrottleis substantially .wide open.

2. In a carburetor having an air entrance, a

outlet from said pump discharging into said mixture chamber at a pointbelow the level of said fuel supply, valve means engaging with said pumpcontrolling said second fuel outlet whereby said second'fueloutiet isonly in operation when the throttle is substantially wide open.

3. In' a downdraft carburetor having an air. entrance, a mixture outlet,a throttle valve therefrom, a piston in said pump, means interconnectingsaid piston with said'throttle, an outlet from said pump discharginginto said mixing chamber said outlet being vented to the atmosphere at apoint above the level in said supply chamber, another outlet from saidfuel chamber discharging into said mixture chamber at a point I belowthe level in said fuel chamber, valve means Bti.

controlling said second outlet interconnected with said throttle so thatsaid second fuel outlet is only, in operation when the throttle issubstan-,

tially wide open. a v

4. In a downdraft carburetor having an air entrance, a mixture outlet, athrottle valve therein, a mixture chamber intermediate the throttle andthe air entrance, a constant level fuel supply chamber, an acceleratingpump fed therefrom,

a piston in said pump, yieldable means interposed chamber, anotheroutlet from said fuel chamber discharging into said mixture chamber at apoint below the level in said fuel chamber, valve means controlling saidsecond outlet interconnected with said throttle so that said second fueloutlet is only in operation when the throttle is substantially wideopen.

5. In a carburetor having an air entrance, a mixture outlet, a throttlevalve therein, a mixture chamber intermediate the throttle and the airentrance, a constant level fuel supply chamber, an accelerating pump fedtherefrom, a piston in said pump, means interconnecting said piston withsaid throttle, an outlet from said pump discharging into said mixingchamber said outlet being vented to the atmosphere at a point above thelevel in saidsupply chamber, an air vented well associated with saidoutlet, another outlet from said fuel chamber discharging into saidmixture chamber at a point below the level in said fuel chamber, valvemeans controlling said second fuel outlet interconnected with saidthrottle so that said second fuel outlet is only-in operation when thethrottle is substantially'wide open.

6. In a carburetor having an air entrance, a mixture outlet, a throttlevalve therein, a mixture chamber intermediate the throttle and the airentrance, a constant level fuel supply chamber, an accelerating pump fedtherefrom, a piston in said pump, yieldable means interposed betweensaid piston and said throttle, an outlet from said pump discharging into.said mixing chamber saidoutlet being vented to the atmosphere at apoint above the level in said supply chamber, an air vented wellassociated with said outlet, another outlet from said fuel chamberdischarging into said mixture chamber at a point below the level in saidfuel chamber, valve means controlling said second fuel outletinterconnected with said throttle so that said second fuel outlet isonly in operation when the throttle is substan tially wide open. a

'7. In a carburetor having an air entrance, a mixture outlet, a throttlevalve therein, amixture chamber intermediate the throttle. and the air20 entrance, a constant level fuel supply chamber, an accelerating pumpfed therefrom, a piston in said pump, means inter-connecting said pistonwith said throttle, an outlet from said pump'discharging into saidmixture chamber at a point below the level of said fuel supply means,valve means engaging with said pump and controlling said outlet wherebysaid fuel outlet is held open when the throttle is substantially wideopen.

8. In a carburetor having an air entrance, a

mixture outlet, a throttle valve therein, a mixture chamber intermediatethe throttle andthe air entrance, a constant level fuel supply chamber,an accelerating pump fed therefrom, a piston in said pump, yieldablemeans interposed between said piston and said throttle, an outlet fromsaid pump discharging into said mixture chamber at'a point below thelevel of said fuel supply means, valve means engaging with said pump andcontrolling said outlet whereby said fuel outlet is held open when thethrottle is substantiallywide open;

' BERT BEARD.

